A reporter from NBC News later asked him to clarify his statement during the briefing. "I think when you come to sarin gas, there was no — he was not using the gas on his own people the same way that Assad is doing," Spicer said.

"[Hitler] brought them into the Holocaust centers, I understand that," he added. "But I’m saying that in the way Assad used them, where he went into towns, dropped them down to innocent — into the middle of towns. It was brought — the use of it. And I appreciate the clarification there, that was not the intent.”

The "centers" Spicer is referring to are presumably the concentration camps in which over six million Jews were exterminated in gas chambers, with poisons like Zyklon-B.

Spicer offered at least three more clarifications after the press conference. "In no way was I trying to lessen the horrendous nature of the Holocaust," Spicer later said. "However, I was trying to draw a contrast of the tactic of using airplanes to drop chemical weapons on innocent people. Any attack on innocent people is reprehensible and inexcusable."

The Anne Frank Center for Mutual Respect said Spicer's comments were "the most evil slur upon a group of people we have ever heard from a White House press secretary," and called for his termination.

Accusations of anti-semitism have surrounded Donald Trump's administration. Steve Bannon, chief strategist and founding member of the alt-right news website Breitbart, has been regularlycovered for his embrace of hate groups. Last month, Trump aide Sebastian Gorka was accused of deep ties to Vitézi Rend, a group which collaborated with the Nazis during the Second World War.